1. Field of the Invention
The present invention relates to a steering wheel pad for use in vehicles and, more specifically, to a pad having a planar switch and a support plate having a rigidity sufficient for supporting the switch.
2. Description of Related Art
A steering wheel pad having a planar switch of the above-mentioned type has been known as described, for example, in Japanese Patent Laid-Open Hei 6-305425.
The conventional steering wheel pad comprises a pad main body (outer cover), a planar switch, and a support plate having a rigidity sufficient to support the switch. A plurality of attaching holes (engaging holes) are formed in the periphery of the support plate passing vertically therethrough, and attaching ribs (engaging legs) for engaging the periphery of the attaching holes of the support plate are formed on the rear face of the pad main body.
However, it has been found that the pad of the above-mentioned structure causes the following problems.
That is, when the support plate of the horn pad is urged upwardly by an air bag of an air bag device, for example, when an air bag folded and contained in the pad main body is loosened or relaxes from its initially assembled state, a gap between pressing protrusions and the planar switch is eliminated even when a horn button bears no load. Thus, the planar switch may make electric contact and thus may operate erroneously.
In view of the above, to maintain a gap between the upper surface of the support plate at a portion inboard of the periphery and the rear face of the pad main body, spacer protrusions are formed on at least one of the rear face corresponding to the periphery of the support plate.
However, there is still a concern that the support plate may distort upwardly in the vicinity of a central portion, thereby inadvertently actuating the planar switch. This drawback may be overcome if the support plate has a sufficient rigidity not to distort due to the urging force of the air bag. However, ensuring sufficient rigidity of the support plate increases the thickness of the support plate considerably, which is not desirable because this conflicts with the demand of reduced weight and compact structure of the horn pad.